I’m not sure how to do what you want with customizing Mint directly, but a possibly simpler alternative solution is to just send two clearly distinguishable USB drives (e.g. label them “1” and “2” with a label maker or get two drives with very different colors) and tell him to install (unmodified) Mint from the first and then have him run a program you provide on the second after that’s done to make the other changes.

I have an older version of TrueNAS on it from when it was still FreeBSD based (instead of Linux). I might replace it with Scale whenever I get around to doing maintenance on it next – or maybe just go to stock Debian or something since I don’t use most of the bells-and-whistles.

I run my NAS that way too. I just mount it and play videos with VLC if I want to watch something I have on it. The main reason I have a NAS is because I ran out of drive bays in my main system a few years ago… Works fine for my needs currently; no need to make it more complicated.

Historically, I don’t know, but personally, I prefer YYYY-MM-DD style dates since they sort naturally in basically all computer software without having to think about it.

If you want to improve significantly, go read someone else’s code and modify it. Try to fix a bug in a program you use, add a feature you want that doesn’t exist already, or even just do something simple for the sake of proving to yourself that you can do it – like compiling it from source and figuring out how to change some small snippet of text in a message box. Even if you don’t succeed, if you put in a serious effort attempting it, you will almost certainly learn a lot from trying.

Edit: changed wording to try to be clearer